1. Field of the Invention
The present invention, in various embodiments, relates generally to probe cards, and, more specifically, to arrangements of probe elements on a probe card.
2. Description of the Related Art
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present invention, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
Generally, NAND memory chips are manufactured and tested in parallel. Conventionally, a grid of die is formed on a substrate using semiconductor manufacturing techniques. Once the die are formed, but before the substrate is diced to form chips, the die are tested for electrical functionality and quality control. Testing certain types of die, such as NAND memory, can take a relatively long time, so a group of die is often tested concurrently, or “in parallel,” with a parallel test probe card. Typically, the probe card includes a plurality of probe elements, which are each configured to test a single die.
Probe cards often have fewer probe elements than there are die on the substrate. Automated test equipment, which test the die via the probe card, have a finite capacity to test die in parallel. For example, signal bandwidth or processing power may limit the number of die that the automated test equipment can test at once. Thus, to test all of the die on a substrate, the die are divided into multiple groups of die, and the die within each group are tested in parallel. During testing, the probe card is usually stepped across the substrate after each group of die is tested, until each of the groups, and thus all of the die on the substrate, have been tested. Each instance of testing a group of die in parallel on a single substrate is generally referred to as a “touchdown.” Thus, for example, half of the die on the substrate may be tested in parallel during a first touchdown, and the other half of the die on the substrate may be tested in parallel during a second touchdown.
Unfortunately, some probe cards do not always use the automated test equipment to its full capacity. Frequently, the probe elements on the probe card are arranged such that some probe elements are not used during some touchdowns. For example, the probe elements may be arranged so that every probe element aligns with a die when a first group of die is tested, but some of these probe elements may be unused when subsequent groups are tested on the same substrate, wasting automated test equipment capacity and reducing throughput.